Behavior and performance of broiler strains reared under semi-intensive system with shaded areas

The matter of animal welfare has led to studies in order to evaluate alternative rearing systems for livestock in order to improve well-being. The semi-intensive system is an alternative method of rearing broilers in which the birds are kept in a poultry house and have free access to a pasture area during the day. It is known that ambient conditions may directly affect the behavior of birds reared in the semi-intensive system. Therefore, this research evaluated the behavior of four broiler strains reared under a semi-intensive system with a shaded area (provided by a black plastic screen - 50%) and the bioclimatic characteristics of this environment when compared with the non-shaded pasture. Thirty-five birds were reared in pens with 4.5 m² and 35 m² of pasture. Ambient variables were measured throughout the day to calculate the indexes of thermal comfort (BGHI and enthalpy). Data was analyzed in a 4 x 2 factorial (4 strains and 2 rearing environments) with 2 repetitions, in order to establish the rate of bird permanence in the pasture. There was an improvement in the ambient conditions of the shaded pasture in the hottest hours of the day (from 10:00 to 14:00 h), i.e., there was a reduction in the mean values of BGHI (approximately 26%) and enthalpy (36%). As a consequence, there was an increase in the rate of permanence in this environment if compared with the non-shaded pasture. Three out of four evaluated strains showed better adaptability to the semi-intensive rearing system.